1. Field of the Invention
This invention relates to scissors jacks with open end construction.
2. Description of Related Art
One means of assembling a jack is by using open end construction. Such open end construction is shown in U.S. Pat. No. 4,802,653, assigned to the assignee of the present invention. While this method is normally used at the trunion ends of the jack, open end construction could be used at any pivot point on the jack. In the structure illustrated in U.S. Pat. No. 4,802,653, the open ends of the legs are bent around the pivot point so as to retain the pivot shaft in the opening. In the typical trunion-channel assembly using open end design as shown in U.S. Pat. No. 4,802,653, once the trunion is inserted into the open end, the end tabs are simply bent toward each other, thus locking the trunion axle in place. Under normal conditions, this is very satisfactory since the linkage members of a jack are in compression when lifting a vehicle. The weakness of this design is that if a linkage member is loaded in tension, the tabs can be spread open again and let the assembly come apart. There are two reasons for this. First, the cross-sectional area of the tabs must be small enough to allow the tabs to bend and therefore are limited to how strong they could be made. Second, when the channel is placed in tension, the tensile force is applied to the tabs in the same plane that the tabs are bent. So as to prevent the tabs from spreading in the prior art jack, it is necessary to use higher strength steel than the jack would normally acquire.